The present invention relates to an ion trap mass spectrometer and ion trap mass analysis method.
A mass analysis apparatus is an apparatus for separating an ionized sample by controlling an electric field or a magnetic field. Nowadays, a mass filter type mass analysis apparatus and a magnetic field type mass analysis apparatus are generally used. These types of mass analysis apparatus ionize the sample continually, and scan the ionized sample passing through the electric field or the magnetic field so as to be mass-separated. On the other hand, another type of mass analysis apparatus was suggested by Paul et al. In this apparatus, the ions are closed in a trap space by a quadrupole radio frequency electric field, and after first accumulating the ions at first, they are mass-separated. For example, such a technology is known by U.S. Pat. Nos. 2,939,952 or 4,540,884, and International Journal of Mass Spectrometry and Ion Processes, 60(1984), Pages 85-98, "RECENT IMPROVEMENTS IN AN ANALYTICAL APPLICATIONS OF ION TRAP TECHNOLOGY".
According to the above technology shown in the aforementioned U.S. Patents, after accumulating once the ions ions, when the ions are mass-analyzed, it becomes possible to mass-analyze them with a high sensitivity. However, as the ions are accumulated, problems are also inherent. That is, as the ions are accumulated over a predetermined time, the time that the ions are confined to the trap domain becomes longer. In the meantime, the ions forming the sample will have reacted with the active molecules etc. in the trap space. Thereby, the sample ions change to other ions, or become extinct, and a reduction in the mass analysis accuracy occurs.